A method and a device for measuring and adjusting compression forces on a press are known from patent specification DE 693 09 610 T2. With this method and device, values of compression force are measured and adjusted in order to obtain a predefined local load distribution as a means of setting the desired localised load distribution irrespective of the specific characteristic data of the press.
In order to produce an exact bending angle on a workpiece finished on a bending press, in particular an edging press, it is also standard practice in the field to use a measuring process to measure the workpiece after bending, in particular the bend angle, and, depending on the thrust depth of the pressing tools detected by a displacement measuring system, to make the requisite correction to the bend angle by changing the thrust depth to obtain the predetermined bend angle during subsequent forming processes. With this type of approach, in which the displacement measuring system is disposed on a separate auxiliary frame in order to take account of force-dependent flexing of the C-shaped side-stands of the machine, production errors occur due to the bending behavior of the press beam, which is also dependent on force as well as the position of the working region on the press beams.
A device for preventing inaccuracies caused by the bending behavior of the press beams during production is also known from patent specification DE 39 21 034 A1, by means of which the bending lines which occur at the co-operating press beams extend substantially parallel and concentric with one another at the instant of the maximum thrust depth of the tools needed to produce the bending angle of the workpiece. However, this approach does not allow a non-symmetrical bending line caused by an eccentric load to be taken into account, which can lead to production failures due to rejects and also rules out the use of many of the advantageous manufacturing options offered by pressing tools used in off-center applications.